'Shelley was an atheist.... He never trifled with the word "God"; he
knew that it meant a personal First Cause, Almighty Creator, and
Supreme Judge and Ruler of the Universe, and that it did not mean
anything else, never had meant anything else, and never whilst the
English language lasted would mean anything else. Knowing perfectly
well that there was no such person, he did not pretend that the
question was an open one, or imply, by calling himself an Agnostic,
that there might be such a person for all he knew to the contrary. He
did know to the contrary; and he said so.
---George Bernard Shaw

'Shelley was an atheist.... He never trifled with the word "God"; he
knew that it meant a personal First Cause, Almighty Creator, and
Supreme Judge and Ruler of the Universe, and that it did not mean
anything else, never had meant anything else, and never whilst the
English language lasted would mean anything else. Knowing perfectly
well that there was no such person, he did not pretend that the
question was an open one, or imply, by calling himself an Agnostic,
that there might be such a person for all he knew to the contrary. He
did know to the contrary; and he said so.
---George Bernard Shaw

'
I think the quote is from the Preface to one of his plays, but I can't remember which play it was at this moment. If I come across it (I re-read Shaw quite a bit, since he was one of the great wits of the English language, and even surprisingly correct in most of what he wrote), I will reply here.
.